iPhone - 从旧的应用程序首选项升级

发布于 2024-10-26 12:26:46 字数 552 浏览 4 评论 0原文

如果我构建一个默认有 2 个字符串的 1.0 应用程序，使用 registerDefaults。
在 2.0 版本中，我决定删除第一个旧字符串，并将第二个旧字符串（更改其密钥字符串）与新的第三个字符串一起移动到数组中。
我该如何处理这个问题以及如何处理可能通过版本对内容进行的更改。

1.0 首选项应为

StringKey    someValue  
DateKey      10/10/2010

1.1 首选项应为

StringKey    someValue  
DateKey      2010/10/10

2.0 首选项应为

Array  
    Item0 is    DateKey        10/10/2010  
    Item1 is    BadString      BadBadValue

原文

If I build a 1.0 app with 2 strings in the defaults, using registerDefaults.
And in a 2.0 version, I decide to remove the first old string, and move the second one (changing its key string) with a new third one into an array.
How may I deal with this and how to deal with the changes that could have been made to the content through versions.

1.0 Prefs should be

StringKey    someValue  
DateKey      10/10/2010

1.1 Prefs should be

StringKey    someValue  
DateKey      2010/10/10

2.0 Prefs should be

Array  
    Item0 is    DateKey        10/10/2010  
    Item1 is    BadString      BadBadValue

分享到QQ

分享到微博

如果你对这篇内容有疑问，欢迎到本站社区发帖提问参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。

发布评论

需要登录才能够评论，你可以免费注册一个本站的账号。

不离久伴 2024-11-02 12:26:46

如果您在应用的 1.0 版中使用过 registerDefaults:，那么这很简单。当您停止注册这些旧值并且它们没有被用户更改时，它们就会从 NSUserDefaults 中消失。

因此，请向 NSUserDefaults 询问所有应转换的对象。如果它们存在，请将它们转换为新格式，将它们保存在 NSUserDefaults 中并删除旧值。

类似这样的东西应该可以工作

// check if you can get the old object. if it's there it was changed by the user
if ([[NSUserDefaults standardUserDefaults] objectForKey:@"OldKey1"]) {
    // old key is present
    id oldObject = [[NSUserDefaults standardUserDefaults] objectForKey:@"OldKey1"];

    id newObject = ... // convert the old object to the new object
    [[NSUserDefaults standardUserDefaults] setObject:newObject forKey:@"NewKey1"];
    [[NSUserDefaults standardUserDefaults] removeObjectForKey:@"OldKey1"];
}
else {
    // old key not there, do nothing
}

// register your new defaults...

如果您还没有使用registerDefaults：，那么您现在遇到了问题。因为您不知道该对象是否被用户更改，或者该对象是否只是您的默认对象。并且您不能仅仅因为该值与默认值具有相同的值就假设该值仍处于默认状态。

但这种情况该怎么办呢？我可能会将值重置为默认值并显示 UIAlert 告诉用户检查首选项，因为我犯了一个错误:-)

If you've used registerDefaults: in version 1.0 of your app it's easy. When you stop to register those old values and they were not changed by the user they disappear from NSUserDefaults.

So ask NSUserDefaults for all objects that should be converted. If they exist convert them to the new format, save them in the NSUserDefaults and remove the old value.

Something like this should work

// check if you can get the old object. if it's there it was changed by the user
if ([[NSUserDefaults standardUserDefaults] objectForKey:@"OldKey1"]) {
    // old key is present
    id oldObject = [[NSUserDefaults standardUserDefaults] objectForKey:@"OldKey1"];

    id newObject = ... // convert the old object to the new object
    [[NSUserDefaults standardUserDefaults] setObject:newObject forKey:@"NewKey1"];
    [[NSUserDefaults standardUserDefaults] removeObjectForKey:@"OldKey1"];
}
else {
    // old key not there, do nothing
}

// register your new defaults...

If you haven't used registerDefaults: you have a problem now. Because you don't know if the object was changed by the user or if the object is simply your default. And you can't assume that the value is still in default state just because it has the same value as the default.

But what to do in this case? I would probably reset the value to default and show a UIAlert that tells the user to check the preferences because I did a mistake :-)

回复收藏 0 原文

~没有更多了~